1. Field
One embodiment of the invention relates to a storage medium driving device such as a hard disk driving device, and especially relates to a micro actuator device and a head suspension assembly incorporated in such storage medium driving device.
2. Description of the Related Art
As disclosed in, for example, Japanese Patent Application Publication (KOKAI) No. 2002-83476, Japanese Patent Application Publication (KOKAI) No. 2002-74870 and Japanese Patent Application Publication (KOKAI) No. 2004-199823, the micro actuator device using a pair of piezoelectric elements is widely known. In the micro actuator device, each piezoelectric element is interposed between an upper and lower pair of support plates. The upper support plate generates strain larger than strain of the lower support plate when a tensile force of the piezoelectric element acts on the lower support plate. A displacement of a head slider occurs based on not only an extension of the support plate resulting from the tensile force of the piezoelectric element but also a bending deformation of the support plate resulting from a difference between the strains.
In such micro actuator device, since the piezoelectric element is interposed between the upper and lower pair of support plates, a fragile piezoelectric element may be surely protected. On the other hand, the above-described bending deformation is linked to a torsional mode and a bending mode of the head suspension. In this manner, a natural frequency of the head suspension decreases. An enlargement of a control band is inhibited.